1. Technical Field
The present invention relates to a spectroscopic sensor and an angle limiting filter.
2. Related Art
In the fields of medical care, agriculture, environment, and so on, spectroscopic sensors are used for diagnosing and inspecting objects. For example, in the field of medical care, a pulse oximeter is used to measure the blood oxygen saturation level using light absorption by hemoglobin. In the field of agriculture, a saccharometer is used to measure the sugar content of fruits using light absorption by sugar.
JP-A-6-129908 discloses a spectroscopic imaging sensor which limits the incident angle with an optical fiber optically connecting between an interference filter and a photoelectric conversion element to thereby limit the transmission wavelength band to the photoelectric conversion element.
However, a related-art spectroscopic sensor has a problem that it is difficult to reduce the size thereof. Therefore, it is difficult to install a number of sensors at desired places or constantly install sensors.